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Medical/biological study (experimental study)

Stress-related endocrinological and psychopathological effects of short- and long-term 50Hz electromagnetic field exposure in rats.

Published in: Brain Res Bull 2010; 81 (1): 92-99

Aim of study (acc. to author)

To study the short-term and long-term effects of 50 Hz electromagnetic field exposure on anxiety- and depression-related behavior of rats in connection with the development of chronic stress state.
Background/further details: Adult male rats (n=32, 8 rats/group (two exposure groups, two sham exposure groups)) were exposed to extremely low frequency electromagnetic fields (50 Hz, 0.5 mT) for 5 days, 8 h daily (short-term exposure) or for 4-6 weeks, 24 h daily (long-term exposure).
The authors hypothesized that long-term extremely low frequency electromagnetic field exposure would result in a chronic stress state accompanied by the permanent activation of hypothalamic-pituitary-adrenal (HPA) axis with consequent anxious and depressive-like behavior (activation of the HPA axis leads to an enhanced secretion of CRF from the hypothalamus provoking the splicing of adrenocorticotropic hormone (ACTH) from proopiomelanocortin (POMC) precursor in the anterior lobe of the pituitary gland. ACTH triggers the secretion of glucocorticoids from the adrenal cortex).
The forced swim test is an animal model often used in the study of depression. It is a 2-day helplessness procedure in which rats swim under conditions in which escape is not possible.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: continuous for 8 hr/day on 5 days
Exposure 2: 50 Hz
Exposure duration: continuous for 24 hr/day during 6 weeks
Exposure 1
Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration continuous for 8 hr/day on 5 days
Exposure setup
Exposure source
Setup Two Helmholtz coils with a radius of 21 cm and 240 turns of 1.4 mm glaze-insulated copper wire, 21 cm apart; 35 cm x 35 cm x 17 cm plastic box with the rats placed between the coils
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 525 V/m minimum measured - -
electric field strength 575 V/m maximum measured - -
magnetic flux density 0.5 mT - measured - +/- 0.025 mT
Exposure 2
Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration continuous for 24 hr/day during 6 weeks
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 525 V/m minimum measured - -
electric field strength 575 V/m maximum measured - -
magnetic flux density 0.5 mT - measured - +/- 0.025 mT
Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated material:
Time of investigation:
  • before exposure
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

Both exposure conditions were ineffective on somatic parameters, i.e. none of the changes characteristic to chronic stress (body weight reduction, thymus involution and adrenal gland hypertrophy) were present.
The data showed that the SHORT-TERM, repeated extremely low frequency electromagnetic field did not induce any sign of chronic stress or any symptom of anxiety-like behavior with the examined parameters in rats.
After continuous LONG-TERM exposure, elevated blood glucose levels, elevated POMC mRNA level in the anterior lobe of the pituitary gland, and enhanced susceptibility for depression-like behavior were detected.
In conclusion, long and continuous exposure to relatively high intensity electromagnetic field (the average intensity of the human exposure is normally much smaller than in the present experiment) may count as a mild stress situation and could be a factor in the development of depressive state or metabolic disturbances.
Study character:

Study funded by

  • Hungarian Scientific Research Fund (OTKA), Hungary

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